package v1ch13.chart;

import javax.swing.*;
import java.awt.*;
import java.awt.font.*;
import java.awt.geom.*;

/**
 * @author Cay Horstmann
 * @version 1.34 2015-06-12
 */
public class Chart extends JApplet {
	public void init() {
		EventQueue.invokeLater(() -> {
			String v = getParameter("values");
			if (v == null) return;
			int n = Integer.parseInt(v);
			double[] values = new double[n];
			String[] names = new String[n];
			for (int i = 0; i < n; i++) {
				values[i] = Double.parseDouble(getParameter("value." + (i + 1)));
				names[i] = getParameter("name." + (i + 1));
			}
			
			add(new ChartComponent(values, names, getParameter("title")));
		});
	}
}

/**
 * A component that draws a bar chart.
 */
class ChartComponent extends JComponent {
	private double[] values;
	private String[] names;
	private String title;
	
	/**
	 * Constructs a ChartComponent.
	 *
	 * @param v the array of values for the chart
	 * @param n the array of names for the values
	 * @param t the title of the chart
	 */
	public ChartComponent(double[] v, String[] n, String t) {
		values = v;
		names = n;
		title = t;
	}
	
	public void paintComponent(Graphics g) {
		Graphics2D g2 = (Graphics2D) g;
		
		// compute the minimum and maximum values
		if (values == null) return;
		double minValue = 0;
		double maxValue = 0;
		for (double v : values) {
			if (minValue > v) minValue = v;
			if (maxValue < v) maxValue = v;
		}
		if (maxValue == minValue) return;
		
		int panelWidth = getWidth();
		int panelHeight = getHeight();
		
		Font titleFont = new Font("SansSerif", Font.BOLD, 20);
		Font labelFont = new Font("SansSerif", Font.PLAIN, 10);
		
		// compute the extent of the title
		FontRenderContext context = g2.getFontRenderContext();
		Rectangle2D titleBounds = titleFont.getStringBounds(title, context);
		double titleWidth = titleBounds.getWidth();
		double top = titleBounds.getHeight();
		
		// draw the title
		double y = -titleBounds.getY(); // ascent
		double x = (panelWidth - titleWidth) / 2;
		g2.setFont(titleFont);
		g2.drawString(title, (float) x, (float) y);
		
		// compute the extent of the bar labels
		LineMetrics labelMetrics = labelFont.getLineMetrics("", context);
		double bottom = labelMetrics.getHeight();
		
		y = panelHeight - labelMetrics.getDescent();
		g2.setFont(labelFont);
		
		// get the scale factor and width for the bars
		double scale = (panelHeight - top - bottom) / (maxValue - minValue);
		int barWidth = panelWidth / values.length;
		
		// draw the bars
		for (int i = 0; i < values.length; i++) {
			// get the coordinates of the bar rectangle
			double x1 = i * barWidth + 1;
			double y1 = top;
			double height = values[i] * scale;
			if (values[i] >= 0)
				y1 += (maxValue - values[i]) * scale;
			else {
				y1 += maxValue * scale;
				height = -height;
			}
			
			// fill the bar and draw the bar outline
			Rectangle2D rect = new Rectangle2D.Double(x1, y1, barWidth - 2, height);
			g2.setPaint(Color.RED);
			g2.fill(rect);
			g2.setPaint(Color.BLACK);
			g2.draw(rect);
			
			// draw the centered label below the bar
			Rectangle2D labelBounds = labelFont.getStringBounds(names[i], context);
			
			double labelWidth = labelBounds.getWidth();
			x = x1 + (barWidth - labelWidth) / 2;
			g2.drawString(names[i], (float) x, (float) y);
		}
	}
}
